Burglar alarm system



Dec. 2, 1952 F. c. w. STELTER BURGLAR ALARM SYSTEM Filed NOV. 13, 1947 Patented Dec. 2, 1952 UNITED STATES PATENT OFFICE 2,619,921 7 BURGLAR ALARM SYSTEM Francis 0. W. Stelter, New York, N. Y. 3 Application November 13, 1947, Serial No. 785,716

3 Claims.

This invention relates to burglar alarm systems i and more particularly to such systems which are especially applicable to portable safes or cabinets for home or office use.

This application is a continuation-in-part of my co-pending application Serial No. 608,668, filed August 3, 1945, now United States Patent 2,438,076, granted March 16, 1948, and has for its general object the provision of a novel and improved alarm system embodying cooperating alarm actuating elements associated with the wall of the safe, cabinet, or other receptacle and an adjacent wall of the room, whereby such connections are clifficult to detect except by careful inspection and also whereby movement of the receptacle for closer inspection will result in setting off the alarm.

Provision is also made for actuating the alarm upon opening the door of the receptacle or movement of certain containers within the receptacle.

Also, the invention contemplates the utilization of said novel actuating elements and connections in systems similar to those described in the above-mentioned co-pending application for combining hold-up alarm features with the burglar alarm set-up; although it will :be apparent that the principles of the present invention may be embodied in a simple burglar alarm circuit with or without supplemental switches and controls.

In its preferred embodiment the invention provides a flush wall switch having a projecting reciprocating spring-pressed pin or button comprising a non-stop actuator of the push-button type, and a spring-pressed actuating plunger extending through the wall of the safe, projecting therefrom, and registering with the pushbutton of the switch when the safe or receptacle is placed in its normal position against the wall. The spacing and adjustment of the several parts is such that in normal safe-closed position, the plunger projects a short distance from the wall of the safe and bears against and depresses the push button of the wall switch. Upon bodily movement of the safe with respect to the wall, the projecting plunger will move away from the button or out of registry therewith and the switch will be actuated in a direction to sound the alarm.

The plunger passes through the wall of the safe and is resiliently urged toward retracted position, the head of the plunger at its inner end bearing against a removable or movable article or container within the safe, whereby tampering with such contents of the safe will permit the retraction of the plunger and-actuate the alarm.

In certain embodiments of theinv'ention the inner container against which the head of the plunger bears may be spring-urged toward the door of the safe and stopped by the door when it is closed. Thus the mere opening of the door of the safe will allow the container to move away from the plunger, the plunger to be retracted and the alarm sounded.

Other objects and features of novelty will be apparent from the following specification when read in connection with the accompanying drawings in which certain embodiments of the invention are illustrated by way of example.

In the drawings,

Figure 1 is a partly diagrammatic view in vertical section through a room and a safe installed therein, showing one embodiment of the novel alarm system;

Figure 2 is a diagram of an alternative circuit which maybe used in the system;

Figure 3 is an enlarged fragmentary vertical sectional view of the safe and wall showing the operative parts of the system to better advantage;

Figure 4 is a similarfragmentary view with a portion of the safe shown in elevation;

Figure 5 is a perspective view of the actuating units showing their relative positions;

Figure 6 is a longitudinal sectional view of the actuator which is installed in the wall of the safe; and t Figure 7 is a fragmentary sectional view, similar to Figure 3, but depicting an alternative installation within the generic scope of the invention. 1

In the embodiment shown in Figure 1 of the drawings the receptacle to. be protected comprises the portable safe I I] having wheels I l which rest upon the floor vl2 of the room in which the safe is installed. This safe is of a kind widely used in homes andsmall ofiices, and is generally not subject to protection by the intricate and expensive burglar alarm systems such as those used in banks and other financial institutions. The wall of the room is indicated at I3 and the safe In is adapted'to be placed in fairly close proximity to this Wall. 1

As already indicated, the alarm, in the preferred form of the invention, 'is adapted to be set off whenever the safe is moved with respect to the wall and also upon the opening of the door of the safe or the disturbance of certain of the contents thereof. In connection with the latter purpose, there is shown Within the safe the drawer l5 which is representative in the exemplary embodiment of any sort of container movable within the receptacle [8.1 .In this instance the container 3 i5 rests upon the floor l6 of the safe and is spaced a short distance from the rear wall I! and from the front door [8 thereof. In order to effectuate the purpose of rendering the alarm responsive to the opening of the door [8, the receptacle I5 is preferably urged forwardly in the safe by means of the leaf spring [9 which is secured as at 28 to the rear wall IT. The spring l9 urges the container l5 toward the door l8 so that the handle 2! or other part of the container presses against the inner face of the door.-

The system illustrated in Figure 1 is very similar to the arrangement covered by the above mentioned co-pending application and is useful for the same purpose, namely to provide a combined burglar and holdup alarm. Set within the wall [3 is a switch 25, the escutcheon plate 28 thereof being applied flush to the face of the wall [3. The switch is of a non-stop type similar to a pushbutton switch and is provided with the projecting pin or button 21, this button being urged outwardly by spring pressure in the usual way. Two leads 29 and 38 extend from the terminals of the switch 25, the lead 29 being connected with one terminal of the relay 32 and the lead 38 being connected to the battery 33, a line 34 serving to connect the battery to the other terminal of the relay 32. The relay 32 controls an alarm circuit which for the present exemplary showing is the same as that set forth in the co-pending application. An armature 35 provides one part of an alarm switch 36, the other pole 31 thereof being connected by the wire 38 to a terminal of the alarm 48 which in this instance is a bell. A wire connects the bell 40 to the battery 42 and this battery is connected to the armature 35 by means of the wire 43. V

It will be seen that during periods when the safe is to be protected from burglary that the switch 25 will be closed so as to maintain the relay 32 energized and the alarm switch 36 open. Thus, means must be provided for maintaining the switch 25 in closed condition and permitting it to open only upon an attempt to burglarize the safe. For this purpose the rear wall I! of the safe i8 is provided with an actuator 50, the actuator being shown in considerable detail on a larger scale in Figures 5 and 6 of the drawings. The exact construction of the actuator may Vary widely but for purposes of example, it is shown as comprising a bushing 52 which may either be threaded through the wall I"! of the safe or may be thrust through a prepared opening in the wall and locked in position by means of the lock nut 53 applied to the threaded end 54 of the bushing, the head 55 bearing against the inner surface of the wall [1.

Passing through the bore of the bushing 52 is the plunger 56,. The plunger has an enlarged head 51 applied thereto which projects rearwardly of the safe, the, shoulder between the head and shank of the plunger 56, limiting the retractive movement of the plunger- The plunger 55 is provided with a head 58 and between the head of the plunger and the head 55 of. the bushing 52 there is compressed av coil spring 60, which serves to urge the heads. apart and thus retract the head 5? of the plunger.

The head 58 of the plunger is adapted to abut the rear end of the container [5 within the receptacle l8 and, when the container is in its normal position, the plunger is. disposed rearwardly so that the head 51 projectsfrom the rear. wall of the safe and depresses,thebuttonflv of the. switch 25. In cases where it is desired to set off the alarm upon the mere opening of the door I8 of the safe, the spring [9 is employed and the container I5 is in contact with both the head 58 of the plunger 55 and the door l8, as clearly shown in Figure l of the drawings. In this example the switch 25 is one which is closed when the button 21 is depressed and open when the button or pin 2'! is projected. Therefore, when in the condition indicated in Figure l, the relay circuit is energized thus de-energizing the alarm circuit. If, however, the door lB of the safe is opened, or in the event the spring [8 is not used, the container I5 is displaced, the spring 58 will urge the plunger 55 forwardly, the projecting end 51 will be retracted, and the button 2'! of the switch 25 projected, thus breaking the relay actuating circuit and allowing the relay switch 35 to close thus setting off the alarm. This condition is clearly shown in Figure 3 of the drawings where the door 18 is open, the spring [9 having pushed the container I5 forwardly so as to allow the plunger '56 to be retracted by the spring 88, whereby the head 51 of the plunger is displaced from bearing pressure against the button 21 of the switch 25. The pin or button 21 may'thus be considered as a trigger means for setting off the alarm when the described conditions are fulfilled.

If an attempt is made to carry on the safe or to move it away from the wall for better access to the contents, or to look for wiring connections, the alarm will also be set off. Referring to Fig-- ure 4 of the drawings it will be seen that the safe It has been moved away from the wall, and, while the plunger 56 is still projected, it also has been displaced from the switch 25 and the "switch button 2! is projected thus setting off the alarm.

Returning to Figure 1, it will be seen that there is provided secret manually operable means for either rendering the safe-controlled portion of the alarm system inoperative during the daytime or for providing a hold-up alarm for use during the same period. This arrangement is similar to the desk-leaf actuated switch system described in the co-pending application. In this embodiment, however, the auxiliary switches areinstalled in a bookcase 55. A switch 86, which may be of the ordinary tumbler variety, is set in the shelf 61 of the bookcase and the tumbler handle or operator 88 is disposed directly in advance of the book 69 so that if the book is shifted forwardly it will move the handle 58 and open the switch.

An alternatively usable switch maybe installed in the top of the bookcase, this switch being of a push-button type similar to the wall switch 25. A vase or other object suggested at 18 is adapted to rest upon the button or switch 56' and keep it closed under normal conditions. Wires l2 connect the switch 68 with two terminals of a double-pole double-throw switch 75. Wires 16 lead from the switch 66" to the opposite end terminals of the switch 15. The switch blades 18 can be alternatively thrown to connect with the opposite pairs of end. terminals, and the two terminals of the blade 18 are connected by means of the wires 19 across the lines 29-and 30 in the relay actuating circuit.

, It will thus be readily seen that either the switch 88 or the switch 88 may be utilized to shunt the relay actuating circuit during the daytime so that the door [8 of the safe may be opened during business hours without setting off the alarm. Similarly, in accordance with the broad principles of the invention covered: in the co-pending application, the switches 88 or- 66' may be utilized to set off a hold-up alarm. If,

sula'ted bushing 81 set in the wall l1.

during ofiice hours or when the safe is open, an attendant were held up, and he was able to displace the book '69 or upset or move the vase 10, the switch 66 or the switch 66' would be opened, thus breaking the relay circuit and setting off the alarm. During the night-time when the burglar alarm feature is involved, the switch 15 can be thrown to disconnect both the switch 66 and the switch 66'.

In Figure 2 of the drawings there is illustrated a much simpler alternative circuit wherein the switch 66 or the switch 66 may be merely utilized as on and oil switches for rendering the burglar alarm switch 25 operable. In this circuit the wire 29' connects one terminal of the switch 25 with the battery 42 and the wire 30 is interrupted for the introduction for either the switch 66 or the switch 65' in series between the wall switch 25 and the alarm bell 40. It will thus be seen that in this case the wall switch 25 will be such that when the plunger, pin, or button 21 is depressed the contact is broken, and when the safe is burglarized the button 21' will be projected in order to close the switch 25 and set off the alarm 40, without the interposition of a relay. In the daytime the switch 66 or the switch 66 (whichever is employed) will be open thus breaking the circuit and de-energizing the alarm system so that access to the safe may be had by the authorized employees.

An alternative arrangement of wall installed alarm devices is shown in Figure 7 of the drawings. In this arrangement the room wall I3 is provided with insulated conductors 80 and 8| to which are connected the leads 29 and 30 of the circuit as shown in Figure 1. Contact heads 82 and 83 are provided on these conductors 80 and BI upon the inner face of the wall 13. Projecting through the rear wall I! of the safe I is a threaded conductor 85 which makes intimate contact with the metal of the safe wall. A similar threaded conductor 86 passes through an in- The projecting ends of the conductors 85 and 86 are adapted to be in normal contact with the points 82 and 83 in the wall 13. A switch 25A is installed within the safe and is provided with a pin or button actuator 21A adapted to be abutted by the rear end of the container l within the safe. A wire 88 connects the conductor 86 with one terminal of the switch 25A and a wire 89 grounds the other terminal upon the body of the safe and thus completes a circuit through the conductor 85 to the leads '29 and 30.

It will thus be seen that normally the button 21A maintains the circuit through the switch 25A closed so that the relay is kept energized. Either the bodily removal of the safe [0 breaking the contacts at the points 82 and 83, or the movement of the container breaking the circuit at the switch A, will set off the alarm.

It will be noted that in all of the embodiments described herein the contacts or switch actuating buttons carried by the wall of the room have outward faces which may be either flush with the exterior surface of the wall or projecting slightly therefrom. It is readily understood how important it is that the faces of these elements are not depressed within or beneath the outer surface of the wall, since if this were the case, movement of the safe in directions parallel with the wall would either damage the actuating parts which are carried by the safe or other receptacle, or damage the wall surface itself.

Various changes and modifications may be -made in the embodiments illustrated and described herein without departing from the scope of the invention as defined by the following tacle, the receptacle itself being positioned in close proximity to the wall of the room in which it is housed; said device comprising a switch set in said wall and having a spring-projected actuator button extending therefrom and adapted to be depressed against the influence of the spring, the outer face of said button when depressed occupying a position which is not beneath the outer surface plane of the wall, a spring-retracted plunger set in the wall of the receptacle and norm-ally disposed in registry and in projected depressing contact with said outer face of said button, a slidable container within said receptacle normally preventing retraction of said plunger, whereby upon displacement of said container, the plunger will retract, releasing the bearing pressure on said button and actuating said switch, the container within the recep tacle causing the plunger normally to be projected to the limit of its movement, said receptacle having a door therein, means for resiliently urging said container within the receptacle away from contact with the plunger and against the inner side of said door, whereby upon opening ,of the door, the container will move away from the plunger, the plunger will be retracted from bearing contact with the button and the switch will be actuated, and also whereby displacement of the receptacle itself either in directions parallel to or away from said wall, will move the plunger away from said button and set off the .alarm.

plane, a second element comprising a tubular guide fixed in the receptacle wall, a plunger reciprocable in said guide with an end normally projecting exteriorly thereof, a head on said plunger projecting into the interior of said receptacle, stop means on said guide and plunger for limiting both the projecting and retracting movements of the latter, spring seats on said plunger and guide, and a coil spring disposed therebetween and serving to urge the plunger to ward retracted position, and means within the receptacle normally obstructing such retractive movement, and maintaining said plunger in projected position in operative contact with the contact face of said room wall supported trigger element, whereby upon movement of the internal obstructing means or of the receptacle as a whole either parallel to or away from said wall such operative contact will be broken.

3. In an alarm system of the class described,

"which includes an alarm, trigger means for setting off the alarm, and operative connectionsbetween said trigger means and said alarm, the combination of a receptacle to be protected having one of its walls disposed in close proximity to the wall of a room, said trigger means including an element carried by said wall of the room and having a contact face parallel with the outer surface plane of said wall and disposed in a position which is not beneath said outer surface plane, a second element comprising a tubular guide fixed in the receptacle wall, a plunger reciprocable in said guide with an enlarged shouldered end normally projecting exteriorly thereof, a head on said plunger projecting into the interior of said receptacle, said shouldered exterior end of the plunger adapted to abut the outer end of said tubular guide to limit the retracting movement of the plunger, a coil spring compressed between the interior head of said plunger and the inner end of said tubular guide and serving to urge the plunger toward retracted position, the ultimate compression of said spring between said head and said guide end serving to limit the 8 projectingv movement of said plunger, and means within the receptacle normally obstructing such retractive movement, and. maintaining said plunger in projected position in operative contact with the contact face of said room wall supported trigger element, whereby upon movement of the internal obstructing means or of the receptacle as a Whole either parallel to or away from said wall such operative contact will be broken.

FRANCIS C. W. STELTER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 215,120 Hall May 6, 1879 1,078,476 Wiggers Nov. 11, 1913 1,250,743 Williams Dec. 18, 1917 1,472,750 Gorman et a1 Oct. 30, 1923 1,902,195 SWahn Mar. 21, 1933 2,438,076 Stelter Mar. 16, 1948 

